This invention relates to scaffolding systems, and more particularly to a pump jack for traveling up and down a pole.
In numerous industries, it is necessary to erect scaffolding both internally as well as externally in order to permit workers to stand at an elevation above ground surface. Typically, a scaffolding system is utilized in the installation of aluminum siding on the exterior of housing. Such scaffolding is typically erected by utilizing pump jack poles which are spaced apart and secured in spaced relationship to the house by means of a brace. Pump jacks are used to ride up and down the poles. The pump jacks typically include support arms on which are extended scaffolding staging. The workers can stand on the scaffolding staging and operate the pump jack to move the staging up and down along the pump jack poles.
Typically a pump jack includes a frame with an upper and lower shackle member supported by the frame. A pump arm is pivotally provided onto the frame which operates the shackles in alternating relationship. The pump arm serves to have the upper shackle in a twist gripping relationship securing onto the pole while it then serves to raise up the frame to step it upward along the pole. The weight then shifts so that the lower shackle twist grips the pole and the upper shackle steps up to a next position on the pole. In this manner, the non-gripping shackle steps up the pole while the opposing shackle grips the pole. To ride the pump jack down the pole, the lower shackle is released from its gripping relationship and the upper shackle is rolled down the pole by means of a handle.
The aforementioned U.S. Pat. No. 4,382,488 described a novel pump jack pole formed of elongated hollow metal with a rubberized surface on only one side of the pole. Such poles were found to be extremely strong, longlasting and easier to manipulate than the standard wooden poles. The aforementioned U.S. Pat. No. 4,463,828 described an improved pump jack which includes features to improve the safety of the pump jack as well as its strength. Such features include the ability to release one of the shackles by means of a foot release pedal avoiding the necessity of bending over and releasing the lower shackle by hand. The patent also described an over-the-center spring loaded handle used to control the rolling down of the pump jack.
The aforementioned features provided in the pump jack have truly served to improve such pump jacks in the industry. Nevertheless additional safety measures are always warranted with respect to the pump jack. For example, the spiral rod utilized to control rolling down of the pump jack along the pump jack pole has a tendency of wearing thereby causing sliding of the pump jack down the pole to result in accidents. Additionally, as such spiral rod wears, it may have a tendency to snap outward thereby further causing additional accidents.
While heretofore pump jacks and pump jack poles were typically utilized in the installation of aluminum siding, such equipment can actually be utilized in other scaffolding needs. For example, in industrial or marine use, scaffolding is often required both internally and externally. In warehouses, where access to various layers of stored objects is required, the use of the pump jack and pump jack poles would be convenient. The platforming staging could be raised and lowered in order to reach the desired objects stored in the warehouse. Similarly, in marine applications, loading and unloading of ships, and other storage locations, could use the present pump jack and pump jack pole arrangement.
When utilizing the pump jack and pump jack pole for industrial use, however, additional strength would be needed for the pump jack in order to support the extra weight of the platforms required. Such extra strength is required not only in the construction of the pump jack itself, but in the operative portions thereof, including the shackles, the platform, etc.
Additional improvements are also warranted in connection with the rod utilized to roll down the pole. While typically spiral rods had been utilized for such purposes, such spiral rods tend to wear, are expensive to manufacture, and have been known to jam. Improvement would also be warranted in such areas as well.
Accordingly, while the aforementioned prior art patents have provided great improvement in the utilization of pump jacks and pump jack poles, additional features, modifications, and improvements are warranted in order to even further extend the use of such eqiupment into industrial and marine areas. Also, additional features are always warranted in order to improve the safety of such equipment.